end period. DNS uses a host’s FQDN to resolve a name to an IP address. The host name does not have to
be the same as the computer name.
3.3.3 Domain Name Space
The DNS database hierarchical naming scheme called a domain name space. Each node in the name space
hierarchy represents a partition of the DNS database. These nodes are referred to as domains, each of which
must have a name as the DNS database is indexed by name. When you add domains to the hierarchy, the
name of the parent domain is appended to the domain, which becomes a child domain or a subdomain.
Consequently, a domain’s name identifies its position in the hierarchy. Thus, the studyguides.vibrant.com
domain name identifies the studyguides domain as a subdomain of the vibrant.com domain and vibrant as a
subdomain of the com domain.
Note: The term domain, in the context of DNS, is not related to domain as
used in the Microsoft Windows Server 2003 directory services. A Windows
Server 2003 domain is a grouping of computers and devices that are
administered as a unit.
The hierarchical structure of the domain name space consists of a root domain, top-level domains, second-
level domains, any subdomains, and host names.
•
The Root Domain is at the top of the hierarchy and is represented as a period (
.
).
•
Top-Level Domains are two or three-character name codes. Top-level domains are organized by
organization type or geographic location. Top-level domains can contain second-level domains and host
names.
•
Second-Level Domains are registered to individuals and organizations for use on the Internet. A second-
level name has two name parts: a top-level name and a unique second-level name. An example is
vibrant.com.
•
Subdomains are created when organizations extend their DNS tree to represent departments, divisions,
or other geographic locations. Subdomains have three name parts: a top-level name, a unique second-
level name, and a unique name representing the department or location. An example is
studyguides.vibrant.com.
•
Host names are the names of specific computers on the Internet or in a private network. A host name is
the leftmost portion of a fully qualified domain name (FQDN), which describes the exact position of a
host within the domain hierarchy. Computer1.studyguides.vibrant.com. is an FQDN and includes the
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